Search

Asymmetric supercapacitors (ASCs) have attracted growing interest and attention in the field of supercapacitors owing to their high energy density and power density. In this work, ordered mesoporous Co3O4 samples with different pore sizes (ca. 20 nm and ca. 70 nm) are prepared via a hard template method. Flexible solid-state ASC devices based on mesoporous Co3O4 with pore size of 20 nm and activated carbon possesses a specific capacitance of 215 mF cm−2 (at 1.5 mA cm−2) and show excellent cycling performance. Electrochemical tests reveal that the mesoporous material with a larger specific surface area, that is, a smaller primary particle size, is more suitable for solid-state ASC device. The results provide a potential electrode material for ACSs. [ABSTRACT FROM AUTHOR]

Dextromethorphan is recognized as a substance of abuse around the world. An estimated 3.1 million people between the ages of 12 and 25 years (5.3%) misused over-the-counter cough and cold medications in 2006. In this study, we developed a serum metabolomic method by gas chromatography-mass spectrometry (GC-MS) to evaluate the effect of abuse of dextromethorphan on rats. The dextromethorphan-treated rats were given 12, 24 and 48 mg/kg (low, medium, high) of dextromethorphan by intragastric administration each day for 3 days. Partial least squares-discriminate analysis revealed that intragastric administration of dextromethorphan induced metabolic perturbations. Compared with the control (healthy) group, the levels of propanoic acid, urea, heptafluorobutanoic acid, 2-hexyldecanoic acid and butanedioic acid of the low group decreased; levels of propanoic acid and heptafluorobutanoic acid of the medium group decreased, while that of benzoic acid increased; and levels of 2-hexyldecanoic acid, glycerol and butanedioic acid of the high group increased. These biomarkers are involved in the citric acid cycle, urea cycle, glycerolipid metabolism and tricarboxylic acid cycle. The results indicate that the metabolomic method by GC-MS may be useful to elucidate abuse of dextromethorphan. According to the pathological changes in the liver at different dosages, dextromethorphan is not hepatotoxic after intragastric administration of 12, 24 and 48 mg/kg for 3 days. [ABSTRACT FROM AUTHOR]

β-SiC is a suitable photocatalyst for hydrogen evolution reaction because of its proper band structure (2.36 eV) and high chemical stability. Porousβ-SiC has a large surface area that can increase the number of reactive sites and shorten the charge transport pathways between the material interior and surface, thereby significantly improving the hydrogen evolution reaction performance. In the present study, hierarchical macroporousβ-SiC monolith composed of nanocrystals was directly prepared using SiO2opal as both template and precursor via the magnesiothermic reduction method at 750 °C. An interfacial magnesiothermic reaction model was presented as well. Theβ-SiC sample exhibited high photoelectric conversion performance and stability as a catalyst for hydrogen evolution. [ABSTRACT FROM AUTHOR]

Seeking high-capacity, high-rate, and durable anode materials for lithium-ion batteries (LIBs) has been a crucial aspect to promote the use of electric vehicles and other portable electronics. Here, a novel alloy-forming approach to convert amorphous Si (a-Si)-coated copper oxide (CuO) core-shell nanowires (NWs) into hollow and highly interconnected Si-Cu alloy (mixture) nanotubes is reported. Upon a simple H2 annealing, the CuO cores are reduced and diffused out to alloy with the a-Si shell, producing highly interconnected hollow Si-Cu alloy nanotubes, which can serve as high-capacity and self-conductive anode structures with robust mechanical support. A high specific capacity of 1010 mAh g−1 (or 780 mAh g−1) has been achieved after 1000 cycles at 3.4 A g−1 (or 20 A g−1), with a capacity retention rate of ≈84% (≈88%), without the use of any binder or conductive agent. Remarkably, they can survive an extremely fast charging rate at 70 A g−1 for 35 runs (corresponding to one full cycle in 30 s) and recover 88% capacity. This novel alloy-nanotube structure could represent an ideal candidate to fulfill the true potential of Si-loaded LIB applications. [ABSTRACT FROM AUTHOR]

Mesoporous NiO nanosheets with a single-crystalline structure were investigated as an oxygen electrode catalyst in a non-aqueous Li–O2 battery. The recharge voltage plateau achieved for the NiO-based Li–O2 battery was ca. 3.95 V, ca. 200 mV negatively shifted compared with that for β-Ni(OH)2 and acetylene black. The reaction mechanism during the charge process for the NiO-based Li–O2 battery was intensively researched. The results of X-ray photoelectron spectroscopy characterization indicated that Li2O2 and Li2CO3 were formed during the discharge process, which can be decomposed after recharge. These demonstrated that the NiO nanosheet exhibited a good activity for the decomposition of Li2O2 and Li2CO3. Furthermore, the results of the gas chromatography-mass spectrometry test reflected two steps of the recharge process, i.e., the oxidation of Li2O2 when the potential was below 4.0 V and the decomposition of Li2O2 and Li2CO3 when the potential was above 4.0 V. Moreover, no obvious performance decay was observed in the NiO-based battery even after 40 cycles when the capacity was limited to 500 mA h g−1, indicating an impressive cycling performance. [ABSTRACT FROM AUTHOR]

For building high-energy density asymmetric supercapacitors, developing anode materials with large specific capacitance remains a great challenge. Although Fe2O3 has been considered as a promising anode material for asymmetric supercapacitors, the specific capacitance of the Fe2O3-based anodes is still low and cannot match that of cathodes in the full cells. In this work, a composite material with well dispersed Fe2O3 quantum dots (QDs, ≈2 nm) decorated on functionalized graphene-sheets (FGS) is prepared by a facile and scalable method. The Fe2O3 QDs/FGS composites exhibit a large specific capacitance up to 347 F g−1 in 1 m Na2SO4 between -1 and 0 V versus Ag/AgCl. An asymmetric supercapacitor operating at 2 V is fabricated using Fe2O3/FGS as anode and MnO2/FGS as cathode in 1 m Na2SO4 aqueous electrolyte. The Fe2O3/FGS//MnO2/FGS asymmetric supercapacitor shows a high energy density of 50.7 Wh kg−1 at a power density of 100 W kg−1 as well as excellent cycling stability and power capability. The facile synthesis method and superior supercapacitive performance of the Fe2O3 QDs/FGS composites make them promising as anode materials for high-performance asymmetric supercapacitors. [ABSTRACT FROM AUTHOR]

Biosensors are widely used in production and life, and can be used in medicine, industrial production, and scientific research. Among them, the detection of pH has always received extensive attention. In this study, we demonstrate the use of a one-step hydrothermal method to prepare Co-FeS2/CoS2 nanomaterials as pH sensor (pH vs. overpotential) for the first time. The proposed pH sensor exhibits outstanding performance in KOH solutions via electrochemical methods with good stability. Overall, the results of this study not only add to the non-noble transition metal electrocatalysis research, but also identify important sensing characteristics for electrocatalysts. [ABSTRACT FROM AUTHOR]

Abstract: Co3O4/graphene nanosheet (GNS) composites were synthesized via the in situ growth of mesoporous Co3O4 nanoparticles on graphene. The as-prepared Co3O4/GNS composites exhibited superior Li-ion battery performance and showed a large reversible capacity, excellent cycling, and good rate capability when used as an anode material in lithium ion batteries (LIBs). The uniform coating of Co3O4 around the graphene surface ensured tight electrical contact, resulting in a material with higher specific capacity and enhanced cycling performance compared with pure Co3O4 electrodes. The composites delivered a reversible capacity of 900mAhg−1 at a discharge current density of 100mAg−1 with good cycling ability. Moreover, the composites showed exceptional high-current charge–discharge performance, achieving 650mAhg−1 at a current density of 1000mAg−1. [Copyright &y& Elsevier]

• A composite photocatalyst of Ag 3 PO 4 particles decorated on modified crispy g-C 3 N 4 flake was fabricated. • Photocatalytic oxygen evolution over Z-scheme heterojunction is roughly 7-fold higher than that in Ag 3 PO 4. • Highly efficient oxygen-evolving performance is mainly attributed to accelerated interfacial charge transfer. • Surface modification and nitrogen atmosphere favor well-organized g-C 3 N 4 nanostructures and enhanced photocatalytic activity. Searching for highly efficient photocatalysts for water oxidation is the footstone for the development of overall water splitting systems and has been actively pursued. The construction of artificial Z-scheme heterojunction photocatalysts has been conclusively proven to be effective in boosting charge transport property and in improving the OER performance. Herein, Ag 3 PO 4 particles anchored on modified crispy g-C 3 N 4 flakes have been successfully fabricated. KOH-assisted surface modification of g-C 3 N 4 flakes and intimate interfacial contact favor the accelerated charge transfer and highly improved OER efficiency. Ultrafast spectroscopy results reveal that modified g-C 3 N 4 with crispy nanostructures possesses more trap-induced long-lived photogenerated holes, which are extremely helpful to combine with photo-generated electrons from the conduction band (CB) position of Ag 3 PO 4 via the specific Z-scheme configuration, leaving more holes in the valence band (VB) of Ag 3 PO 4 for the enhanced OER. Superb oxygen-evolving performance highlight the great promise of Z-scheme Ag 3 PO 4 -based heterojunctions in solar-driven photocatalytic water splitting. [ABSTRACT FROM AUTHOR]

• 1D CdS/2D Ti3C2 MXene Schottky heterojunction was successfully fabricated. • In situ constructed Schottky photocatalyst exhibits enhanced HER performance. • Ultrathin 2D MXene enhances light absorption and accelerates charge transport. • The specific Schottky interface is responsible for the improved HER activity. Benefiting from excellent metallic conductivity, full-spectrum solar energy absorption and rich active sites on the surface, atomically thin two-dimensional transition metal carbide (2D MXene) shows great promise in improving solar-to-hydrogen efficiency and has drawn intense interest in the field of photocatalysis. However, controllable construction of ultrathin 2D MXene-based heterojunction photocatalysts still remains a significant challenge. Herein, one-dimensional (1D) CdS nanorod/2D MXene nanosheet heterojunctions with well-defined nanostructures and strong interfacial coupling are fabricated by in situ assembling solvothermally-generated CdS nanorods on ultrathin Ti 3 C 2 MXene nanosheets. Due to their specific interface characteristics, 1D/2D Schottky heterojunction is capable of providing accelerated charge separation and a lower Schottky barrier for solar-driven hydrogen evolution from water splitting. As expected, the Schottky-based photocatalyst is 7-fold more active in the illuminated hydrogen evolution reaction (HER) than pristine CdS nanorods, implying the synergistic effects between n-type semiconductor CdS and highly conductive 2D Ti 3 C 2 MXene nanosheets. [ABSTRACT FROM AUTHOR]

• Nanoparticles in groundwater were investigated using TEM. • Nanoparticles with different contents of ore-forming elements can be grouped into three main types. • A relationship between metal-bearing nanoparticles and concealed orebodies was demonstrated. • Classification of ore-related nanoparticles was important for the detection of mineralization information. The characterization of nanoparticles in groundwater is recognized as an important tool that can be applied to mineral exploration. In this paper, we investigate the concealed orebodies of the Qujia gold deposit in the Jiaojia orefield of eastern China by analyzing ore-related nanoparticles in groundwater using transmission electron microscopy. The nanoparticles contain variable amounts of ore-related elements (e.g., Ag, Cu, Zn, La, Ce, Pb, Pt, and S). Some of these elements are rarely found in natural settings unrelated to orebodies or mineral extraction, but are strongly linked to concealed orebodies in the study area. These nanoparticles, which are diverse in their shapes, aggregated features, and degrees of crystallinity, can be grouped in terms of composition as: (i) native metal nanoparticles, (ii) metal-based nanoparticles, and (iii) carrier nanoparticles associated with trace elements. We propose that these three main types of nanoparticles enable the efficient transport of ore-forming elements in groundwater. The results of this study provide insights into the migratory behaviour of ore-related nanoparticles in groundwater, and our methods could be applied for detecting deep-seated mineral deposits. [ABSTRACT FROM AUTHOR]

Graphitic carbon nitride (g-C 3 N 4) is sprouted as an efficient and cost-effective visible-light-responsive photocatalyst for yielding hydrogen from water splitting. However, a brisk recombination of light-induced electron-hole (e− - h+) pairs in the bulk g-C 3 N 4 effectuate poor quantum efficiency in the hydrogen evolution reaction (HER). The shuttle redox mediator manifests ample potential in accelerating photo-induced carrier segregation and in boosting charge transport in the HER. Here, we report that exploiting Ag/Ag(I) and Fe(III)/Fe(II) shuttle redox mediators, the hydrogen-evolving rate of the aforementioned g-C 3 N 4 nanosheets can reach 3213.3 μmol g−1 h−1 under visible-light irradiation, which is eight times higher than that of pure g-C 3 N 4 (404.82 μmol g−1 h−1). The effective coupling between a hydrogen-evolving catalyst and appropriate shuttle redox mediators significantly improves the HER-photocatalytic performance of native g-C 3 N 4 nanosheets. Density functional theory calculations show that the presence of Ag/Ag(I) and Fe(III)/Fe(II) shuttle redox mediators can effectively promote H atom adsorption and facilitate a H 2 O reduction reaction. This work envisages a new and deft approach for contriving high-performance g–C 3 N 4 –based photocatalysts for highly efficient solar-to-fuel conversion. • Ag/Ag(I) and Fe(III)/Fe(II) shuttle redox were loaded on the surface of g-C 3 N 4. • The modified g-C 3 N 4 showed excellent photocatalytic H 2 activity and chemical stability. • Double shuttle redox on the g-C 3 N 4 boost the separation of photoexcited charges. [ABSTRACT FROM AUTHOR]

• 2D g-C 3 N 4 nanosheet was fabricated by the supramolecular assembly approach. • Assembled 2D g-C 3 N 4 photocatalyst demonstrates enhanced HER performance. • 2D nanostructure accelerates charge transport and solar-to-hydrogen efficiency. • Ultrafast spectroscopy reveals charge carrier dynamics in 2D g-C 3 N 4 nanosheets. Two-dimensional graphitic carbon nitride (2D g-C 3 N 4) nanostructures have been the focus of substantial research interest recently owing to their promising photoactive properties for use in solar-to-fuel conversion. However, the synthesis of 2D g-C 3 N 4 nanomaterials remains a significant challenge. Here we successfully synthesized 2D g-C 3 N 4 nanosheets via a supramolecular chemistry approach. 2D g-C 3 N 4 nanostructures not only enhance the visible light-harvesting property but also provide more catalytic sites for improved hydrogen evolution reaction (HER). More importantly, we describe experimental findings concerning the dynamics of charge and energy transfer by using ultrafast spectroscopy in combination with in-situ electron spin resonance (ESR) characterization. The mechanistic investigation reveals that the introduction of a benzene-substituted melamine motif can remarkably accelerate the electron-hole separation and suppress the recombination of photogenerated charge carriers. The carrier separation dynamics is expected to be tailored by engineering the surface and morphology of g-C 3 N 4 , which favors enhanced solar photocatalytic HER efficiency. [ABSTRACT FROM AUTHOR]

The Fenton reaction is recognized as an effective technique for degrading persistent organic pollutants, such as the emerging pollutant trimethoprim (TMP). Recently, due to the excellent reducibility of active hydrogen ([H]), Pd-H 2 has been preferred for Fenton-like reactions and the specific H 2 activation of Pd-based catalysts. Herein, a heterogeneous Fenton catalyst named the hydrogen-accelerated oxygen reduction Fenton (MHORF@UiO-66(Zr)) system was prepared through the strategy of building ships in the bottle. The [H] has been used for the acceleration of the reduction of Fe(III) and self-generate H 2 O 2 . The systematic characterization demonstrated that the nano Pd 0 particle was highly dispersed into the UiO-66(Zr). The results found that 20 mg L -1 of TMP was thoroughly degraded within 90 min in the MHORF@UiO-66(Zr) system under conditions of initial pH 3, 30 mL min -1 H 2 , 2 g L -1 Pd@UiO-66(Zr) and 25 μM Fe 2+ . The hydroxyl radical as well as the singlet oxygen were evidenced to be the main reactive oxygen species by scavenging experiments and electron spin resonance. In addition, both reducing Fe(III) and self-generating H 2 O 2 could be achieved due to the strong metal-support interaction (SMSI) between the nano Pd 0 particles and UiO-66(Zr) confirmed by the correlation results of XPS and calculation of density functional theory. Finally, the working mechanism of the MHORF@UiO-66(Zr) system and the possible degradation pathway of the TMP have been proposed. The novel system exhibited excellent reusability and stability after six cyclic reaction processes., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Severe shuttle effect of soluble polysulfides and sluggish redox kinetics have been thought of as the critical issues hindering the extensive applications of lithium-sulfur batteries (LSBs). Herein, one-dimensional boron nitride (1D BN) fibers with abundant pores and sufficient N-vacancy defects were synthesized using a thermal crystallization following a pre-condensation step. The 1D structure of BN facilitates unblocked ions diffusion pathways during charge/discharge cycles. The embedded pores within the polar BN strengthen the immobilization of polysulfides via both physical confinement and chemical interaction. Moreover, the highly exposed active surface area and intentionally created N-vacancy sites substantially promote reaction kinetics by lowering the energy barriers of the rate-limiting steps. After incorporating with conductive carbon networks and elemental S, the as-prepared S/Nv-BN@CBC cathode of LSBs deliver an initial discharge capacity of up to 1347 mAh g-1 at 200 mA g-1, while maintaining a low decay rate of 0.03% per cycle over 1000 cycles at 1600 mA g-1. This work offers an effective strategy to mitigate the shuttle effect and highlights the significant potential of defect-engineered BN in accelerating the reaction kinetics of LSBs., (© 2024 Wiley‐VCH GmbH.)

Aqueous zinc-ion batteries (AZIBs), with the merits of high safety, environmental friendliness, abundant resources, and competitive energy density are recognized as a promising secondary battery technology and are anticipated to be a great alternative to organic lithium-ion batteries (LIBs). However, the commercial application of AZIBs is severely hindered by intractable issues, including high desolvation barrier, sluggish ion transport kinetics, growth of zinc dendrite, and side reactions. Nowadays, cellulosic materials are frequently employed in the fabrication of advanced AZIBs, because of the intrinsically excellent hydrophilicity, strong mechanical strength, sufficient active groups, and unexhaustible production. In this paper, we start from reviewing the success and dilemma of organic LIBs, followed by introducing the next-generation power source of AZIBs. After summarizing the features of cellulose with great potential in advanced AZIBs, we comprehensively and logically analyze the applications and superiorities of cellulosic materials in AZIBs electrodes, separators, electrolytes, and binders with an in-depth perspective. Finally, a clear outlook is delivered for future development of cellulose in AZIBs. Hopefully, this review can offer a smooth avenue for future direction of AZIBs by means of cellulosic material design and structure optimization., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationship that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Background: The tumour microenvironment and cirrhotic liver are excellent sources of cancer-associated fibroblasts (CAFs), which participate in carcinogenesis. Thus, it is important to clarify the crosstalk between CAFs and HCC cells and the related mechanism in regulating carcinogenesis., Methods: Human hepatocellular carcinoma (HCC) tissues and matched adjacent normal tissues were obtained from HCC patients. Immunohistochemistry, Western blotting (WB) and RT-qPCR were performed to detect the expression of SCUBE1. The roles of SCUBE1 in inducing stemness features in HCC cells were explored and investigated in vitro and in vivo. Student's t tests or Mann-Whitney U tests were used to compare continuous variables, while chi-square tests or Fisher's exact tests were used to compare categorical variables between two groups., Results: SCUBE1 was confirmed to be highly expressed in CAFs in HCC and had a strong connection with stemness and a poor prognosis. In addition, CAFs were found to secrete SCUBE1 to enhance the malignancy of HCC cells and increase the proportion of CD133-positive cells. Silencing SCUBE1 expression had the opposite effect. The Shh pathway was activated by SCUBE1 stimulation. Inhibition of cyclopamine partially reversed the stimulating effect of SCUBE1 both in vivo and in vitro. Moreover, based on the RT-qPCR, ELISA and WB results, a high SCUBE1 expression level was found in HCC tissue and serum., Conclusion: This study revealed that CAFs-derived SCUBE1 can enhance the malignancy and stemness of HCC cells through the Shh pathway. This study aims to provide new perspectives for future HCC studies and provide new strategies for HCC treatment., (© 2022. The Author(s).)

Accumulating evidence demonstrates that the expression levels of programmed cell death protein 1 (PD-1) and programmed death ligand 1 (PD-L1) are regulated at the various levels, including transcription, post-transcriptional modification and post-translational modifications (PTMs). The PTMs of PD-1/PD-L1 contain phosphorylation, ubiquitination, methylation, glycosylation and palmitoylation. Recently, PD-L1 was reported to be acetylated at Lys263 site by p300 and was deacetylated by histone deacetylase 2 (HDAC2). Acetylation of PD-L1 prevented its translocation to the nucleus and led to a reduction of the nuclear portion of PD-L1, resulting in evading immune surveillance of tumor cells. In this review article, we briefly describe the PTMs of PD-1/PD-L1 and mainly summarize the novel findings of PD-L1 acetylation in tumor cells. Moreover, we discuss the associations of PD-L1 acetylation and ubiquitination, phosphorylation and methylation. Furthermore, we highlight that targeting acetylation of PD-L1 by HDAC inhibitors might be useful for enhancing tumor immunotherapy., Competing Interests: None., (AJCR Copyright © 2021.)

The fabrication of high-performance and stable electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is of importance for sustainable water-splitting technologies. Herein, the cobalt (Co) nanoparticles and molybdenum carbide (Mo 2 C) heterostructures anchored N-doped carbon (Co/Mo 2 C@NC-800) was designed as bifunctional electrocatalyst for overall water splitting via a simple pyrolysis approach for metal organic frameworks (MOFs) precursor. This composite shows a remarkable performance for HER and OER with a small overpotential of 121 mV and 311 mV at 10 mA cm -2 , respectively. When the optimized electrocatalyst was employed as both anode and cathode for overall water splitting in a two-electrode system, the electrolyzer achieves a low cell voltage of 1.67 V at 10 mA cm -2 in 1 M KOH, as well as a superior and stable long-time operation of 30 h. The promising hybrid material demonstrates excellent electrocatalysis performance due to effective combination of the best of both worlds: Mo 2 C with remarkable HER performance and Co nanoparticles with excellent OER activity. The Mo 2 C possesses strong hydrogen binding energy and Co exhibits prominent electrical conductivity, thus the construction of heterostructures achieves more active sites with different functions and significantly boosts HER and OER process. The novel and effective synthesis strategy provides new insights into the design of outstanding non-noble metal bifunctional electrocatalysts for overall water splitting., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Ultrasmall and homogeneous bimetallic PdxBi nanoalloys are well distributed on a Vulcan carbon support by a facile, low-cost synthetic strategy. The electrochemical activity of the as-prepared homogeneous PdxBi nanoalloy/carbon black nanocomposites is closely related to the content of Bi, revealing their excellent electrocatalytic performance for selective oxidation of monohydric alcohols and vicinal diols in alkali medium.

A highly sensitive triple-amplification assay for the detection of microRNA (miRNA) let-7a is reported in this work. The assay relies on the formation of magnetic two-dimensional DNA/Fe 3 O 4 nanosheet networks initiated by the target miRNA-associated hybridization chain reaction. The Fe 3 O 4 nanosheets in the DNA/Fe 3 O 4 networks display peroxidase-like catalytic activity towards a colorimetric reaction, thereby producing a highly sensitive signal for the quantification of let-7a. Under optimal conditions, the assay achieved a detection limit of 13 aM at a signal-to-noise ratio of 3 and a linear calibration plot between 0.05 fM and 12 nM. Successful attempts were made in the quantification of let-7a in serum samples.

Ordered porous RuO 2 materials with various pore structure parameters are prepared via a hard-template method and are used as the carbon-free cathodes for Li-O 2 batteries under the voltage cutoff cycle mode. The influences of pore structure parameters of porous RuO 2 on electrochemical performance are systematically studied. Results indicate that specific surface area and pore size determine the specific capacity and round-trip efficiency of Li-O 2 batteries. Too small pores cause pore blockage and hinder the diffusion pathways of Li + and O 2 , thereby causing small specific capacity and high overpotentials. Too large pores weaken the mechanical property of porous RuO 2 , thereby causing the rapid decrease in capacity during electrochemical reaction. The Li-O 2 battery based on the RuO 2 cathode with an average pore size of 16 nm (RuO 2 -16) exhibits a high round-trip efficiency of ≈75.6% and an excellent cycling stability of up to 70 cycles at 100 mA g -1 with a voltage window of 2.5-4.0 V. The superior performance of RuO 2 -16 can be attributed to its optimal pore structure parameters. Furthermore, the in situ differential electrochemical mass spectrometry test demonstrates that RuO 2 can effectively reduce parasitic reactions compared with carbon materials., (© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)